First principles phase diagram calculations for the octahedral-interstitial system αTiOX, 0≤X≤1/2

▸ First principles phase diagram calculation for the suboxide system Ti[]1−XOX; 0≲X≲1/2. ▸ The prediction of Devil's staircase order-disorder behavior in Ti6O and Ti3O. ▸ The prediction of a Ti2O ground-state that is not CdI2-related. ▸ The prediction that no CdI2-related phase is stable at elevated temperature.